This invention relates to a method of, and an apparatus for, periodically lubricating the links of a circulating chain guided around chain wheels.
Chain lubricating devices are known comprising their own lubricating chain wheel which is placed and held by a frame in a position on the chain where a sufficiently high chain tension for driving the lubricating chain wheel exists, such as near one of the non-driven chain guide wheels. On each of the flat surfaces of the lubricating chain wheel, there is a ring having radially oriented oil outlet openings distributed around its entire circumference. The rings are each divided into eight oil chambers, and each chamber supplies four nozzles with lubricating oil. There is a piston for adjoining pairs of oil chambers, which thus operates eight nozzles, four on the left and four on the right side of the wheel.
The axle of the lubricating chain wheel is journalled on the side walls of the frame so that the chain wheel adopts an off-centre position to allow a sufficiently large space between the chain wheel and one of the side walls for a bush with connections for the hydraulic pipes which supply the oil distributor rings, and also a bush seating each oil piston and a cam actuating the piston via an abutment arm. The lubricating oil, supplied by gravity from a storage vessel above the lubricating apparatus via an inlet valve, is applied periodically onto the chain at preset time intervals.
The lubricating components mounted on the axle of the lubricating chain wheel driven by the circulating chain are at times subjected to large rotational forces which, at high chain speeds, leads to uncontrolled empty running of the lubricating oil ducts and the applicator nozzles. A pressure-stable oil column therefore cannot form in the feed system to the nozzles, although such a column is absolutely necessary if extremely small hydraulic piston strokes are required to react in a rapid sequence. Known lubricating devices also include a pneumatically driven pump and therefore require a compressed air source, which in many industrial situations is not available.
The periodic lubricating of a chain dependent, for example, upon a timing relay, frequently leads in the set time allowed to more than just one lubrication of some of the lubricating points on the chain and to overlubrication, which is particularly disadvantageous in the foodstuffs and packaging industries. Furthermore, every lubrication point (pin end) does not receive the same quantity of oil, which moreover should be distributed uniformly over the largest possible area of the chain pin, since inaccurate application beyond the necessary region reduces the lubrication gaps and thus increases the oil demand.
The task underlying the present invention is to avoid the foregoing disadvantages and to provide a method and apparatus for periodically lubricating a circulating chain with which it becomes possible to lubricate up to 10,000 lubrication points (chain pins) per minute in such a way that, with a considerably reduced oil consumption and independently of time, the chain links each receive the same quantity of oil only once per chain revolution and at each end of a pin only in the region of the chain pin between the side bars, which small quantity can be distributed, even at high chain speeds, over the largest possible area of the chain pin.